Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds genuinely useful behavioral context beyond that: what fields come back, the has_pharmacy existence flag vs. the service indicators, and explicitly what is NOT covered (no pharmacy hours or patient data). This anticipates agent queries the annotations cannot express.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with what the tool returns, then input handling, then the optional service filter. Sentences are dense but each carries distinct information (scope, precedence, exclusions). Slightly long, but nothing is redundant with structured fields.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With an output schema already describing return values, annotations covering safety, and full schema coverage, the description is complete: it explains input precedence, return scope, exclusions, and the optional service filter. Nothing an agent needs to invoke it correctly is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the baseline is 3, but the description adds meaning not present in the schema: the mutual-exclusivity/precedence of zip, address, and lat/long, and the note that the service code vocabulary matches the response's services field. That resolves real ambiguity for a 5-param, 0-required tool.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description names a specific verb and resource (CVS store locations for a location input) and enumerates exactly what is returned, including the has_pharmacy flag and service list. It clearly distinguishes itself from sibling CVS tools (cvs_product, cvs_search, cvs_categories) by scoping to store-finding. An agent can select it without opening the schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

It gives clear input-selection guidance (zip, or address, or lat/long together) and an explicit precedence rule when multiple are supplied (zip > address > lat/long). It also states scope exclusions (no pharmacy hours, pharmacy phone, or prescription data). It stops short of naming an alternative sibling tool to route to, so not a full 5.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.